The present invention relates to a photomultiplier tube comprising a photocathode, a first dynode intended to receive the photoelectrons emitted by the photocathode, an electron multiplier device of the "leaf" type, and a device for coupling the first dynode to the multiplier device.
The invention is particularly advantageously applied in the field of photomultiplier tubes incorporating an electron multiplier device of the "leaf" type.
The general technical problem to be solved in the case of the photomultiplier tubes exhibiting a first dynode which, most frequently, is of large size in such a manner as to ensure a good collection of the photoelectrons, and a leaf-type multiplier device, is to couple the first dynode to the multiplier device in such a manner that the secondary electrons emitted by the first dynode can arrive, with low loss, at the leaf-type multiplier.
A solution to this general technical problem is given, for example, in the Japanese Pat. application No. JP-59-167946, which describes a photomultiplier tube according to the preamble, the first dynode of which is cylindrical, of generatrices orthogonal to an axis, the axis of the multiplier device being parallel to the said axis. In this known tube, the coupling between the first dynode and the leaf-type multiplier device is provided by placing between the first dynode and the multiplier device a set of three intermediate dynodes serving, to some extent, as deflectors of the electron beam in the direction of the multiplier.
Nevertheless, the known photomultiplier tube of the prior art exhibits the disadvantage of a relatively large longitudinal space requirement, due principally to the presence of the said intermediate dynodes which, moreover, make the assembly and the construction of such a tube more complex.
Further, the technical problem to be solved by the subject of the present invention is to propose a photomultiplier tube comprising a photocathode, a first cylindrical dynode of generatrices orthogonal to an axis and which is intended to receive the photoelectrons emitted by the photocathode, a multiplier device of the "leaf" type, and a device for coupling the first dynode to the multiplier device, the axis of the multiplier device being parallel to the said axis, with a view to providing a photomultiplier tube, the longitudinal space requirement of which would be reduced and the construction facilitated by a more advantageous arrangement of the leaf-type multiplier in relation to the first dynode.